libstdc++: Fix libstdc++ build on some targets [PR107811]
fast_float library relies on size_t being 32-bit or larger and float/double
being IEEE single/double. Otherwise we only use strtod/strtof.
In 3 spots I've used fast_float namespace stuff unconditionally in one
function, which breaks the build if fast_float is disabled.
2022-11-23 Jakub Jelinek <jakub@redhat.com>
PR libstdc++/107811
* src/c++17/floating_from_chars.cc (__floating_from_chars_hex): Guard
fast_float uses with #if USE_LIB_FAST_FLOAT and for mantissa_bits and
exponent_bits provide a fallback.
diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc
index be1e105..3f5d4d4 100644
--- a/libstdc++-v3/src/c++17/floating_from_chars.cc
+++ b/libstdc++-v3/src/c++17/floating_from_chars.cc
@@ -783,11 +783,16 @@
using uint_t = conditional_t<is_same_v<T, float>, uint32_t,
conditional_t<is_same_v<T, double>, uint64_t,
uint16_t>>;
+#if USE_LIB_FAST_FLOAT
constexpr int mantissa_bits
= fast_float::binary_format<T>::mantissa_explicit_bits();
constexpr int exponent_bits
= is_same_v<T, double> ? 11
: is_same_v<T, fast_float::floating_type_float16_t> ? 5 : 8;
+#else
+ constexpr int mantissa_bits = is_same_v<T, float> ? 23 : 52;
+ constexpr int exponent_bits = is_same_v<T, float> ? 8 : 11;
+#endif
constexpr int exponent_bias = (1 << (exponent_bits - 1)) - 1;
__glibcxx_requires_valid_range(first, last);
@@ -945,8 +950,11 @@
else if (mantissa_idx >= -4)
{
if constexpr (is_same_v<T, float>
+#if USE_LIB_FAST_FLOAT
|| is_same_v<T,
- fast_float::floating_type_bfloat16_t>)
+ fast_float::floating_type_bfloat16_t>
+#endif
+ )
{
__glibcxx_assert(mantissa_idx == -1);
mantissa |= hexit >> 1;
@@ -1130,6 +1138,7 @@
}
if constexpr (is_same_v<T, float> || is_same_v<T, double>)
memcpy(&value, &result, sizeof(result));
+#if USE_LIB_FAST_FLOAT
else if constexpr (is_same_v<T, fast_float::floating_type_bfloat16_t>)
{
uint32_t res = uint32_t{result} << 16;
@@ -1156,6 +1165,7 @@
| ((uint32_t{result} & 0x8000) << 16));
memcpy(value.x, &res, sizeof(res));
}
+#endif
return {first, errc{}};
}
